Pre-enrollment baseline patient evaluation will include clinical assessment, assessment of New York Heart Association (NYHA) functional class, blood tests, chest x-ray, echocardiography, magnetic resonance imaging (MRI), electrocardiogram, cardiopulmonary exercise testing, submaximal exercise testing, and quality of life assessments. Blinded central evaluation will be performed for measures of cardiopulmonary exercise testing, blood tests, Holter Monitors and cardiac imaging.